Comminution mill

ABSTRACT

The specification discloses a comminution mill, or disintegrator, in which material to be comminuted is introduced into a housing at one side, while the comminuted material is withdrawn from the housing at the other side. Within the housing, a rotor is rotatably mounted and the periphery of the rotor is provided with grinding blades which run inside a grinding ring mounted in the housing and forming therewith a grinding region. On the inlet side of the rotor, the rotor is provided with radially extending vanes which form fan blades and precrushing blades and direct the material entering the inlet toward the aforementioned grinding region and impel it therethrough toward the outlet side of the housing. Inside the housing on the outlet side of the rotor there are arranged guide vanes which direct the material from the grinding region toward the outlet of the housing. The rotor is, furthermore, provided with sifting blades extending axially from the rotor on the outlet side thereof in the region of the housing surrounding the aforementioned outlet so that material passing from the aforementioned guide vanes to the outlet comes within the range of the sifting blades. The rotor is, furthermore, provided with apertures extending therethrough in the region radially outwardly from the aforementioned sifting blades so that large particles will be engaged by the sifting blades and be driven thereby back through the apertures to the inlet side of the rotor and will again pass through the aforementioned grinding region.

United States Patent Voelskow et al.

[ COMMINUTION MILL [75] Inventors: Peter Voelskow, 6550 Bad Kreuznach; Karl Sch'aifer, 6551. Neu-Bamberg uber Bad Kreuznach, in der Lohe 22, both of Germany; Jacques Pestre, F-81 Labruguiere, Tarn, France [73] Assignee: Inter-Wood-Maschinen GmbH &

Co. KG, Bad Kreuznach, Germany [22] Filed: .May 12, 1971 [21] App1.No.: 142,670

[30] Foreign Application Priority Data May 15, 1970 Switzerland ..7335/70 [52] U.S. Cl ..24l/52, 241/244 [51] Int. Cl ..B02c 13/13 [58] Field of Search ..241/52, 55, 79.2, 241/793, 80, 244, 255

[56] References Cited UNITED STATES PATENTS 745,075 11/1903 Schutz....' ....24l/52 2,591,141 4/1952 Dulait .241/52 X 2,939,638 6/1960 l-laigh et al. ..241/52 3,173,618 3/1965 Merges et a1. .....24l/55 3,273,809 9/1966 Horstman ..24l/244 Primary Examiner Granville Y. Custer Jr. A ttorney- Melvin A. Crosby 7\ 11 3,731,883 1 May 8, 1973 [57] ABSTRACT The specification discloses a comminution mill, or disintegrator, in which material to be comminuted is introduced into a housing at one side, while the comminuted material is withdrawn from the housing at the other side. Within the housing, a rotor is rotatably mounted and the periphery of the. rotor is provided with grinding blades which run inside a grinding ring mounted in the housing and forming therewith a grinding region. On the inlet side of the rotor, the rotor is provided with radially extending vanes which form fan blades and precrushing [blades and direct the material entering the inlet toward the aforementioned grinding region and impel it therethrough toward the outlet side of the housing. Inside the housing on the outlet side of the rotor there are arranged guide vanes which direct the material from the grinding region toward the outlet of the housing.

The rotor is, furthermore, provided with sifting blades extending axially from the rotor on the outlet side thereof in the region of the housing surrounding the aforementioned outlet so that material passing from the aforementioned guide vanes to the outlet comes within the range of the sifting blades. The rotor is, furthermore, provided with apertures extending therethrough in the region radially outwardly from the aforementioned sifting blades so that large particles will be engaged by the sifting blades and be driven thereby back through the apertures to the inlet side of the rotor and will again pass through the aforementioned grinding region.

The present invention relates to a comminuting mill, or a disintegrator, and is particularly concerned with a mill of this type in which larger particles that pass through the grinding region of the mill and approach the outlet of the mill are deflected back to the incoming side of the grinding region of the mill.

Comminuting mills, or disintegrators, are widely employed for the size reduction of materials. Such mills, however, have heretofore been characterized in that particles are discharged therefrom which are insufficiently reduced in size and, therefore, too large for the intended purpose. A number of solutions have been offered to overcome this problem of the insufficiently reduced particles,'but such solutions have called for complicated, expensive constructions and have not been widely used in the art.

In heretofore known comminuting mill arrangements the drawback has also existed that the grinding time, and which is the time during which the material to be ground remains in the grinding region of the mill, cannot be selected or adjusted. Further, such mills according to the prior art employ stationary grinding rings which are subjected to extremely heavy wear and tear and, thus, have relatively short life. It has been common, heretofore, to make such rings in the form of cast segments.

With the foregoing in mind, the primary objective of the present invention is the construction of a comminuting mill in which the drawbacks referred to above 7 are eliminated.

A still further object of the present invention is the provision of a comminuting mill in which superior results are obtained.

It is also an object of this invention to provide a comminuting mill in which the length of the grinding time for the material passing through the mill can be selected, or adjusted.

Still another. object of this invention is the provision of a comminuting mill in which coarse particles escaping from the grinding region of the mill toward the outlet thereof are deflected back to the inlet side of the grinding region to be retreated therein.

A still further object of the present invention is the provision of a comminuting mill which is simple in construction and inexpensive to manufacture and which does not easily fall into disorder and which can readily be serviced when necessary.

The exact nature of the present invention will become more apparent upon reference to the following detailed specification taken in connection with the accompanying drawings in which:

FIG. 1 is a partial vertical sectional view through a comminuting mill constructed according to the present invention; and

FIG. 2 is a fragmentary view showing one manner in which the grinding blades on the rotor of the mill could be adjustably connected thereto.

BRIEF SUMMARY OF THE INVENTION In the mill of the present invention, a generally discshaped housing is provided having a central inlet on one side and a central outlet on the other side and a rotor rotatably mounted in the housing and rotating between the inlet and the outlet. The rotor is provided on the inlet side with radial vanes which form fan blades and precrushing blades and which drive material introduced into the inlet, together with air, toward the periphery of the rotor. The periphery of the rotor is provided with grinding blades and the housing is provided with a grinding ring surrounding the rotor so that the grinding blades and grinding ring form a grinding region through which the material to be comminuted passes in the axial direction from the inlet side of the rotor to the outlet side thereof.

On the outlet side of the rotor, the housing is provided with guide vanes extending from the grinding region toward the outlet in the housing. The rotor is providedwith axial sifting blades on the outlet side extending toward the outlet in the housing and disposed near the periphery of the outlet and in the path of material guided by the guide vanes in the housing toward the outlet. The sifting blades permit fine material to pass therethrough to the outlet to be withdrawn from the housing, while larger particles are impacted by the sifting blades and are driven backwardly away from the outlet.

The rotor is provided with apertures extending from the outlet side of the rotor to the inlet side thereof and located radially outwardly from the aforementioned sifting blades, so that the said larger particles which are struck by the sifting blades will be driven through the apertures to the inlet side of the rotor and, thus, will again pass through the grinding region of the mill. Advantageously, the rotor is offset toward the outlet side of the housing immediately outwardly from the sifting blades and this facilitates the movement of the larger particles through the aforementioned apertures to the inlet side of the rotor.

Advantageously, the guide vanes in the housing are mounted on a cover member which is detachable from the housing and which results in a simple and inexpensive construction and one which permits ready servicing of the mill, if necessary.

Advantageously, the grinding blades are adjustably mounted on the rotor in order to adjust the grinding conditions that exist in the grinding region of the mill.

The grinding ring is preferably formed of war resistant steel segments with grooves therein extending axially of the housing. Such groove can beformed in the steel segments by a countersinking or a cold hobbing operation. The grooves of the grinding ring can also be formed ofhighly alloyed tool steel bars or even of a harder metal, such as a cemented carbide material, and can be attached by brazing or by cementing, such as by means of an epoxy cement.

DETAILED DESCRIPTION OF THE INVENTION Referring to the drawings somewhat more in detail, in FIG. 1 the mill will be seen to comprise a housing of generally disc or drum shape and having an incoming chute 2 communicating with an inlet opening in about the center of the housing on the inlet side 10 thereof. On the other side of the housing, and opposed to inlet 2, is a discharge outlet 3 from which the comminuted material is withdrawn from the mill.

A shaft 4 extending axially into the mill supports a grinding rotor 5. Grinding rotor 5 is formed of an outer imperforate ring portion 7 and a central imperforate hub 9 with apertures 8 disposed therebetween is mounted on shaft 4. Radial spokes between apertures 8 support portion 7 on hub 9.

On the inlet side of the rotor there are provided the generally radial vane means 11 which serve as fan blades and as precrushing blades. The vane means 11 can be fixed to hub 9 or to ring 7, or to both thereof, as may be desired.

On the outlet side of the grinding rotor and extending substantially axially therefrom are sifting blade means 12 which are located immediately radially outwardly from outlet 3. Sifting blades 12 are located radially inwardly, however, of the apertures 8 and which apertures extend through the rotor from the outlet side thereof to the inlet side thereof.

Preferably, the ring 7 is somewhat thicker than hub 9 so that the rotor is, in effect, offset toward outlet 3 in the region radially outwardly of sifting blades 12 so that the apertures 8 are at least partially coextensive with sifting blades 12 in the axial direction.

The mill housing, on the outlet side, comprises a detachable cover member 13 in which the outlet 3 is formed. On the inside of cover member 13 there are provided the guide vanes 14 which extend from the grinding region at the outer periphery of the rotor toward outlet 3 but terminate radially outwardly from sifting blades 12. The material emerging from the grinding region of the mill is directed toward outlet 3 by the vanes 14 together with air being blown through the mill by-vanes l 1.

The aforementioned grinding blades 6 cooperate with grinding ring means 15 mounted inside the mill housing in surrounding relation to the periphery of the rotor to the mill. The grinding ring means is provided with grooves 16 which extend in the generally axial direction of the housing from the inlet side thereof toward the outlet side thereof. The grinding ring means 15 is preferably formed of segments of steel which is abrasion resistant. The grooves 16 may be formed in the steel by cold working of steel, such as by countersinking or cold hobbing the grooves therein. However, the grooves of the grinding ring means can also be formed from bars of a highly alloyed tool steel, or from other harder materials, such as cemented carbide material. The segments of the grinding ring are preferably secured fixedly in the housing, such as by brazing or by cement, such as epoxy cement.

In operation, the material to be ground is delivered to the inlet of the housing via the chute 2 and is precrushed by blades 11 and is impelled radially outwardly in the housing, together with air, toward the grinding region defined by grinding blades 6 and the grinding ring means 15. The material being ground and the air is moved axially through the grinding region and is then directed by guide vanes 14 toward outlet 3 of the housing. This material passes through the region in which sifting blades 12 are moving and these blades allow the finely ground material and the air to pass therethrough to the outlet while the larger particles are engaged by blades 12 and impelled backwardly away from outlet 3. The larger particles thus impelled backwardly by blades 12 pass through the apertures 8 to the inlet side of the rotor and again pass through the grinding region for further reduction thereby.

It has been mentioned that the blades 6 can be adjustably mounted on ring 7 and one such arrangement s illustrated IIl FIG. 2 wherein each blade 6 has a shank 17 thereon extending radially of the rotor and having an annular recess portion 18 that is engaged by an cecentric clamp pin 19 rotatably mounted in rotor 7. By loosening pins 19, the blades 6 can be adjusted angularly about the axes of the respective shanks 17 and, upon tightening up of pins 19, the blades will again be fixedly clamped to the rotor. The blades 6 could be adjusted as to the angle of inclination with respect to a radial plane, alternatively, if so desired.

Modifications may be made within the purview of the appended claims.

What is claimed is:

1. In a comminuting mill: a disc-shaped housing having a central inlet on one side and a central outlet on the other side and a rotor rotatable on the axis of said housing between said inlet and outlet, said mill being adapted to receive material to be comminuted at said inlet and to discharge comminuted material at said outlet, grinding blades on the periphery of said rotor and grinding ring means in said housing surrounding said rotor and forming together with said grinding blades a grinding region, first vane means on the rotor on the inlet side thereof arranged between said inlet and said grinding region, second vane means in said housing on the outlet side of said rotor arranged between said grinding region and said outlet, sifting blade means on said rotor on the outlet side thereof extending in the axial direction across the path of material guided by said second vane means toward said outlet, and aperture means in said rotor extending from the outlet side thereof to the inlet side thereof and positioned in the region of said rotor radially outwardly from said sifting blade means.

2. A comminuting mill according to claim 1 in which said housing comprises a cover member on the discharge side thereof, said second vane means being carried by said cover member.

3. A comminuting mill according to claim 1 in which said grinding blades are adjustably mounted on said rotOl'.

4. A comminuting mill according to claim 1 in which said rotor is formed of a hub portion and an outer ring portion and spokes connecting said portions and forming said aperture means therebetween.

5. A comminuting mill according to claim 4 in which said ring portion projects axially beyond said hub portion on the side toward said outlet, said sifting blades being mounted on said hub portion and being partly coextensive in the axial direction with those ends of said aperture means which face the outlet side of said housing.

6. A comminuting mill according to claim 5 in which said aperture means incline in the radially outward direction from the ends thereof which face the outlet side of said housing to the ends thereof which face the inlet side of said housing. 

1. In a comminuting mill: a disc-shaped housing having a central inlet on one side and a central outlet on the other side and a rotor rotatable on the axis of said housing between said inlet and outlet, said mill being adapted to receive material to be comminuted at said inlet and to discharge comminuted material at said outlet, grinding blades on the periphery of said rotor and grinding ring means in said housing surrounding said rotor and forming together with said grinding blades a grinding region, first vane means on the rotor on the inlet side thereof arranged between said inlet and said grinding region, second vane means in said housing on the outlet side of said rotor arranged between said grinding region and said outlet, sifting blade means on said rotor on the outlet side thereof extending in the axial direction across the path of material guided by said second vane means toward said outlet, and aperture means in said rotor extending from the outlet side thereof to the inlet side thereof and positioned in the region of said rotor radially outwardly from said sifting blade means.
 2. A comminuting mill according to claim 1 in which said housing comprises a cover member on the discharge side thereof, said second vane means being carried by said cover member.
 3. A comminuting mill according to claim 1 in which said grinding blades are adjustably mounted on said rotor.
 4. A comminuting mill according to claim 1 in which said rotor is formed of a hub portion and an outer ring portion and spokes connecting said portions and forming said aperture means therebetween.
 5. A comminuting mill according to claim 4 in which said ring portion projects axially beyond said hub portion on the side toward said outlet, said sifting blades being mounted on said hub portion and being partly coextensive in the axial direction with those ends of said aperture means which face the outlet side of said housing.
 6. A comminuting mill according to claim 5 in which said aperture means incline in the radially outward direction from the ends thereof which face the outlet side of said housing to the ends thereof which face the inlet side of said housing. 